Raman determination of uniformity of multilayer Si/Ge structures with Ge quantum dots

Spectra of Raman scattering by optical phonons of multilayer Si/Ge structures with Ge quantum dots (QDs) grown by means of low-temperature (Ts = 250 0C) molecular beam epitaxy are studied. Two types of Ge islands are observed: pseudomorphic to a Si matrix, and those in which the strains are relaxed non-uniformly. Application of polarization measurements allows us to separate the phonon lines corresponding to these two components of a QD array. A method for the quantitative estimation of the degree of uniformity of the QD array, determining the integrated electron-hole spectrum of the structure, is proposed.